GIS, Remote Sensing, Spatial Urban Growth, Nairobi Metropolitan Region, Sustainable Development
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American Journal of Geographic Information System 2017, 6(2): 64-82 DOI: 10.5923/j.ajgis.20170602.03 Spatial Monitoring of Urban Growth Using GIS and Remote Sensing: A Case Study of Nairobi Metropolitan Area, Kenya Monica Machuma Katyambo*, Moses Murimi Ngigi Institute of Geomatics, GIS and Remote Sensing, Dedan Kimathi University of Technology, Nyeri, Kenya Abstract Nairobi city expanded spatially leading to the formation of the 32,514 km2 Nairobi Metropolitan Area. The region faces rapid urbanization challenges and lacks reliable data for urban planning. This study is aimed at monitoring the urban land cover using GIS and Remote Sensing techniques. Three different land cover maps produced at ten year epochs between 1995 and 2015 were used to evaluate and analyse urban growth visually and quantitatively. Spatial metrics indices and the Annual Urban Spatial Expansion Index were employed in the quantitative analyses. Urban land cover increased from 408.99 km2 to 763.79 km2 and to 2,187.82 km2 with annual growth rates of 8.4% and 17.2% in the two study period epochs. The areas had annual spatial expansion indices of 4.58% and 6.32% respectively in the periods 1995- 2000 and 2000-2015. Radial-axial expansion of built-up areas along transport routes led to the expansion of urban areas into agricultural and forest land. The region’s spatial plan forecasted an urban land cover of 1,717.72km2 by the year 2030, yet by the year 2015, the urban area was 2,187.82 km2. These growth characteristics will have an effect on the location of the proposed Cyber city, Knowledge-cum-Health city and the Aerotropolis, as proposed in the spatial planning concept of the NMR. The spatial analysis of the NMR growth trends could support in the urban growth management mechanisms and plans for sustainable development. Keywords GIS, Remote Sensing, Spatial urban growth, Nairobi Metropolitan Region, Sustainable development and social development program, proposed flagship projects 1. Introduction to spur development across the country, one being the creation of six metropolitan areas covering the main cities. Urbanization is the process by which large numbers of The NMR project was the first be set up with a vision to grow people become permanently concentrated in relatively small and develop into a world class African metropolis capable of areas. It is induced by physical geography, living and creating sustainable wealth and offer a high quality of life to property costs, demand for more living space transportation, its residents, the people of Kenya and investors by the year and lack of proper planning policies [2]. The world is rapidly 2030 [7]. It was earmarked for rapid economic development urbanizing and cities are experiencing the dynamic processes since it plays an important role locally in the Kenyan of urbanization and globalization [8]. A large percentage of economy, regionally, as well as globally. the world’s population reside in metropolitan areas of Urban growth, being a land use/cover change phenomena developing countries [18] thereby raising a need of urban from a non-urban category to an urban category [3] is a planning. Kenya being one of Africa’s fastest urbanizing dynamic and complex phenomenon revealing economic countries had 215 urban centers in the year 2009 with development. Spatial temporal urban growth indicates the Nairobi as the capital city [10]. Twenty four (24) of these spatial and temporal dimensions of land cover/ use change at urban centers are located within the Nairobi Metropolitan the level of the urban landscape [5]. Urban land covers a Region (NMR). smaller area compared to other land covers but its impact to Previous land use/cover studies revealed that there was the surrounding environment is higher. It alters the land use unsustainable sprawl of Nairobi city [12]. It is estimated that pattern, land values and the intensity of site use [15]. Urban by the year 2030, 61.5% of the urban population will live growth combined with urban sprawl, inadequate within the NMR [13]. The Kenya Vision 2030, an economic infrastructure and land use planning have posed a challenge in the Nairobi Metropolitan Region-NMR [8]. * Corresponding author: [email protected] (Monica Machuma Katyambo) Urban growth generates a lot of problems and challenges Published online at http://journal.sapub.org/ajgis economically, socially and environmentally [13]. It has both Copyright © 2017 Scientific & Academic Publishing. All Rights Reserved negative and positive effects on the ecological and social American Journal of Geographic Information System 2017, 6(2): 64-82 65 systems. Urbanization when ignored may intimidate caused by infill and by the vertical dimension of space was sustainable development. [6]. Urban expansion in the NMR not considered in assessing urban growth with regard to has induced significant socio-economic, environmental and settlement expansion. health challenges [4] raising a need of urban planning. This study answers questions such as where did urban Urban development is a large resource consumant that growth occur in the NMR between 1995 and 2005?; at what calls for proper planning and monitoring [10]. Lack of rate and how much land was converted to urban land cover information about urban spatial growth taking place in within the study period?; and which urban growth theory different parts of the metropolitan region has limited the explains the expansion. These questions were answered process of urban and regional planning and development with the aid of spatial metrics(total area-TA, class area-CA, management [8]. Urbanization in the NMR has led to high number of patches-NP, patch density-PD, largest patch-LP, land prices, low forest cover, and encroachment on largest patch index-LPI, mean patch size-MPS), urban conservation areas such as the Athi and Tana River growth indicators (annual urban spatial expansion catchments [9]. index-AUSEI) and through visual interpretation of the The Ministry of Nairobi Metropolitan Development resultant urban land cover maps. Spatial metrics are (MoNMeD) developed a spatial plan to determine how the numerical indices to describe structure and patterns of a NMR was to develop. The plan was to guide and coordinate landscape [14]. They quantify and describe the underlying development of infrastructural facilities and services and for structure and patterns of urban landscape from geospatial the specific control of the use and development of land [10]. data [16]. It proposed spatial modelling for the NMR through six new The study will enable spatial planners to determine the towns as new growth centres in the national economy as possibility to implement proposed development programs as well as to accommodate new activities meant to decongest it is possible to identify the available and lost land cover as Nairobi city [7]. The selection of the proposed new towns a result of new urban development. With this information, locations were based on accessibility from the road network, urban growth management mechanisms such as urban topography, availability of low productivity agricultural growth boundaries and delineation of land uses can be land, low interference with ecologically sensitive and implemented. conservation areas, and good potential for landscaping. This left out the crucial urbanization factor. Spatial planning requires information on the existing 2. Materials and Methods land-use/land-cover pattern, its spatial distribution and changes [17]. Urbanization determines the implementation To acquire the information needed in monitoring spatial of spatial planning proposals and of course has an impact on urban growth in the NMR, GIS and Remote Sensing sustainability of urban ecosystems. For the comprehensive technologies were used. land-use planning of urban areas, current and accurate land 2.1. The Study Area use information is vital for spatial planning and management [11]. Monitoring urban growth in the NMR is necessary for This study focuses on the Nairobi metropolitan region implementing appropriate strategies regarding the urban (NMR) comprising of four (4) out of the forty seven (47) planning decision making process and in redrawing urban counties in Kenya namely: Nairobi, Kiambu, Machakos, policies in the NMR. and Kajiado (Figure 1). The area is a highly urbanizing The main objective of this study was to monitor growth region with 24 urban centres. Nairobi city being the most in the urban land cover by analyzing the spatial-temporal dominant is the core of the metropolis. The region extends urban land use/cover changes that occurred in the region over an area of approximately 32514km2 that substantially before and after the creation of the Nairobi Metropolitan depend on Nairobi city for employment and social facilities. Area using GIS and remote sensing techniques. Landsat The NMR is strategically located as a central gateway to images were characterised, mapped and quantified to reveal the East and Central African region as well as its changes in the built-up land cover from which changes in positioning on the Northern corridor and the Cape to Cairo growth and pattern were evaluated and analysed. highway. International trunk roads A104, A109 pass The study focuses on the expansion of urban areas as sign through the area enabling movement of traffic to/from of economic development. Remote sensing and GIS Mombasa to neighbouring landlocked countries of Uganda, technologies are used since they are a proper and effective Rwanda, South Sudan and Ethiopia. These characteristics tool to understand and present the phenomenon. Mapping present significant strengths for the region as it provides unplanned urban expansion provides a “picture” of where useful access points to various markets in Africa and this type of growth is occurring; its negative effects and particularly for the Indian Ocean islands and South Asia. suggests mitigation measures [17]. Accurate mapping of The Metro Vision 2030 divided the NMR into urban lands and monitoring urban expansions are significant foursub-regions: Core Nairobi (Nairobi county), the for optimum urban analysis in urban planning of Northern Metro (Kiambu county), the Eastern Metro metropolitan regions [1].